Liver damage and failure due to various forms of hepatic injury is a significant source of overall morbidity and mortality in the US and worldwide. Persistent hepatic injury occurs during viral hepatitis, fatty liver disease (steatohepatitis), drug or alcohol and autoimmune induced hepatitis. Clinical conditions are numerous where hepatic injury is a vital component of multi-organ failure caused by complex trauma including blast injury, septic shock, and graft failure after liver transplantation often leading to death of the patient. Enzymatic assays of serum ALT and AST, widely used as part of a `hepatic function' panel, are neither sensitive nor particularity specific to the liver and do not assess the magnitude of liver injury or predict outcome. If liver damage is imminent, tissue biopsies are routinely used for diagnosis. This indicates an explicit clinical need for non-invasive biomarkers for early detection of liver injury with enhanced diagnostic information. We propose here the continuation of the development of novel liver specific biomarkers which are easily detected in serum and can be used for early diagnosis of patients with liver injury and aid in monitoring of potential liver toxicity in patients during drug treatment. Our biomarkers can also be used in preclinical studies of hepatotoxicity. We identified several novel liver-specific biomarkers in rat models of hepatic injury with the argininosuccinate synthase (ASS) and hepatic estrogen sulfotransferases (EST-1) being the most sensitive markers which rapidly accumulated in blood and correlated with the severity of damage. In Phase I, a prototype SW ELISA for quantifying ASS in serum was developed, and sufficient data were obtained demonstrating the greater biomarker sensitivity and specificity in experimental models of liver injury compared to ALT/AST. Also, we provided the proof-of-concept data indicating the diagnostic and prognostic value of serum ASS in human patients with several types of liver diseases and hepatic injury. In Phase II, a ready-to-use ELISAs Kits for ASS and EST-1 will be developed and validated in preclinical studies in rat models of liver injury and hepatotoxicity. Sufficient supplies of the assay components (e.g. antibodies and antigens) will be produced under quality assured conditions. We will characterize the diagnostic potential of ASS and EST-1 assays in human patients with various types of liver diseases and hepatic injury. The biomarker levels will be that will be correlated with clinical data including liver biopsy, serological and laboratory data with an emphasis on hepatic injury severity, disease progression and outcome. The accuracy, sensitivity, specificity and diagnostic/prognostic values of ASS/EST-1 will be assessed and compared with ALT/AST. These analyses will be used to support a pre-IDE application to the FDA for validation of these assays as diagnostic tools and further commercialization. The deliverables of this Phase II project will be quality assured ELISA assays for two liver injury biomarkers, and clinical data supporting the use of the biomarkers as tools for aid in the diagnosis of liver injury and monitor the magnitude of liver toxicity far beyond information obtained from ALT/AST measurements. [unreadable] [unreadable] PUBLIC HEALTH RELEVANCE: Liver health is a major component of human wellbeing. Many environmental chemicals, pathogens, drugs or excessive alcohol can harm the liver and affect its function. An estimated 5.5 million Americans have chronic liver diseases, including viral hepatitis, alcoholic liver disease or hepatic cancer, which frequently lead to liver failure and requires liver transplantation. Moreover, increasing numbers of prescription drugs such as cholesterol-lowering drugs and over-the-counter medications, including acetaminophen, can potentially cause liver toxicity and, thereby, require medical liver function checks. For the last 30 years, two enzymes, serum ALT and AST have been used in hepatic function panels to assess liver health. However, ALT/AST are neither sensitive nor specific to detect mild injure, assess magnitude of damage or predict outcome. Banyan Biomarkers is developing predictive bioassays such as ASS and EST-1 that can help determine liver insults early on in patients that suffer from liver toxicity from therapeutic drugs or environmental toxins. These assays will provide a novel diagnostic/prognostic tools and serve as "safety biomarkers." according to the FDA. [unreadable] [unreadable] [unreadable]